Alopecia areata (AA) is an immunologically mediated disease characterized by non-scarring
hair loss (Madni and Shapiro, 2000). AA is presented by rapid and complete hair loss in
one or more round or oval patches, usually on the scalp, beard area, eyebrows, eyelashes,
and less commonly, on other hairy areas of the body (Berker et al., 2010 and James et
al., 2011) Alopecia areata is a T-cell-mediated autoimmune disease. There is a
complicated interplay between loss of immune privilege in the hair follicle,
autoimmune-mediated hair follicle damage, and activation of inflammatory pathways that
have been argued to explain the development of this disorder, but the exact
pathophysiology of AA remains unknown. Hair follicles are infiltrated by autoreactive CD8
and CD4 T lymphocytes, which attack hair follicle-derived autoantigens while sparing the
stem compartment (Rajabi et al., 2018).
Alopecia areata can be treated with topical and/or intralesional corticosteroids, which
are the treatment of choice. Anthralin, minoxidil, coal tar, and topical immunotherapy
are examples of other topical treatments. Systemic immunosuppressants such as
cyclosporine, systemic steroids, Janus kinase inhibitors, and methotrexate may be
considered in severe resistant cases (lee and lee, 2017).
Intralesional triamcinolone acetonide is preferred in cases of AA , as it is well known
as anti-inflammatory and interferes with local immunity of the skin, which helps in the
recovery of the disease, but if used in wrong technique or given in a high dose, it might
cause all the side effects of corticosteroid, especially skin atrophy (Berker et al.,
2010).
Lactic acid is a member of alpha-hydroxy acids. It has been used in the treatment of many
skin diseases, like AA and vitiligo. Lactic acid stimulates spontaneous secretion of
vascular endothelial growth factor (VEGF) by human reconstructed epidermis. VEGF is an
angiogenic cytokine involved in angiogenesis and wound healing and stimulates the growth
of hair follicles resulting in recovery of AA. Other studies suggest that lactic acid may
act through its irritant effect (Al-Tammimy, 2005).
Vitamin D interacts with the innate and adaptive immune systems in a variety of ways, the
majority of which contribute to its downregulation (Nancy and Yehuda, 2009). It has a
powerful effect on T and B lymphocytes, influencing their activation responses (Arnson et
al., 2007).
All cells of the immune system express 1,25-dihydroxyvitamin D3 receptors (VDRs) and are
therefore vulnerable to calcitriol-mediated modulation. Vitamin D3 has the ability to
influence the migration and maturation of different dendritic cell subtypes and their
production of chemokines and cytokines, giving them an immunoregulatory and tolerogenic
role (Illescas-Montes et al., 2019) It has been shown that VDRs are highly expressed in
the keratinocytes of human hair follicles and the absence of their expression is
associated with reduced hair follicle growth and epidermal differentiation. Reduced VDR
expression in the hair follicles of affected areas has also been observed in studies of
AA patients' scalp (Çerman et al., 2015).
Microneedling (MN) is a technique that comprises puncturing the skin repeatedly with
sterile microneedles (Iriarte et al., 2017). It promotes hair regeneration by triggering
stem cells in the hair bulge, which results in the generation of growth factors. It also
improves blood circulation to the hair follicles and influences the local immune cells
(Chandrashekar et al., 2014). Moreover, combining MN with applied topical drugs
facilitates their absorption through the microchannels created within the epidermis
(Fertig et al., 2018).
